The present study is a contribution to the physical and chemical analysis of water, sediments and fish in order to determine the pollution status of Léré lake in Western Mayo-Kebbi (Chad). The study investigates parameters such as temperature, pH, conductivity, turbidity, dissolved oxygen, BDO5 and CDO. Likewise, concentrations of trace elements known as heavy metals Cu, Cd, Pb, Fe, Mn, As, Zn, Ni and Cr of which some are especially toxic were determined in water, sediments and fish. Results of heavy metals analysis: Cu (0.95 - 3.90 mg/l), Pb (0.13 - 0.75 mg/l), Ni (0.40 - 6.40 mg/l), Cr (0.03 - 0.50 mg/l), As(0.03 - 0.18 mg/l), Cd (0.07 - 0.15 mg/l) and Zn (0.98 - 15.30 mg/l) as well as data on CDO (26-50 mg/l) and BDO5 (17-34 mg/l) showed that water pollution of the Léré lake was very significant though consumed by surrounding populations. The same report can be made on strongly contaminated sediments: Ni (5.9 mg/Kg), As (2.71 mg/Kg), Cr (6.60 mg/Kg), Cd (0.50 mg/Kg) and Mn (0.26 mg/Kg). Over all, within the framework of this study, fish flesh was less contaminated than fish gills.

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